JP3082363B2 - Extra fine line drawing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for drawing ultrafine wires, and more particularly to a slip ratio for drawing ultrafine wires such as gold, copper, and aluminum used for connecting circuits of ICs (integrated circuits) and transistors. Related to the method of controlling.

[0002]

2. Description of the Related Art As is well known, a bonding wire used for circuit connection of an IC or a transistor is 10 to 40 .mu.m.
An ultrafine wire of about m, such as gold, copper, or aluminum, is used. 2. Description of the Related Art Conventionally, as a drawing apparatus for producing this kind of ultrafine wire, the one shown in FIG. 1 is structurally known.

In FIG. 1, a lubricating oil tank 12 has a die holder 3 holding a plurality of dies 2 at substantially equal intervals.
And two capstans 4, 4 ′ arranged substantially parallel to both sides of the die holder 3. Extra fine line 1
From the supply side to the discharge side of the lubricating oil tank 12, it is passed around the first capstan 4, passed through the first one of the dies 2, and then passed around the second capstan 4 ', It is again passed around the first capstan 4, then the next die, again passed around the second capstan 4 ', and so on. The dies are alternately passed through and discharged. Dice 2
Their diameter gradually decreases from the supply side to the discharge side, so that the diameter of the ultrafine wire 1 is reduced each time the die 2 is passed one after another.

A capstan driving motor 5 is connected to one of the capstans 4, 4 ′ (in the illustrated example, the first capstan 4). It is also connected to another capstan (in the illustrated example, the second capstan 4 ′), and the two capstans 4, 4 ′ are simultaneously rotated by this motor. A tach generator 6 is directly connected to the shaft of the motor 5. The tach generator 6 has a rotation speed signal (a voltage proportional to the rotation speed) representing the rotation speed of the motor 5 and therefore the capstans 4 and 4 ′. ). Furthermore, a rotary encoder 8 for calculating a slip ratio is directly connected to the axis of the second capstan 4 ′, and the rotary encoder 8 also outputs a rotation speed signal (rotational speed proportional to the rotation speed) of the motor 5. (Pulse of the specified frequency). The frequency is used after being converted into a voltage at the time of calculation.

A take-up spool 19 for winding the discharged ultrafine wire 1 is disposed outside the discharge side of the drawing apparatus. The take-up spool 19 is rotated by a take-up spool driving motor 9. It has become so. Further, a tach generator 10 is directly connected to the motor 9, and the tach generator 10 generates a rotation speed signal indicating the rotation speed of the take-up spool 19. Furthermore, a rotary encoder 11 for calculating a slip ratio is connected to the take-up spool 19, and this rotary encoder 11 also generates a rotation speed signal indicating the rotation speed of the take-up spool 19.

[0006] The take-up spool 19 and the aforementioned related parts are supported on a carriage 25 of a traverse device.
Thus, each time the ultrafine wire 1 is wound on the take-up spool 19 by one stage, the direction in which it moves in the lateral direction is reversed and reciprocated.

[0007] Here, assuming that the diameter of the capstan is d, the rotation speed of the capstan is n, the winding diameter of the ultrafine wire wound on the winding spool is D, and the rotation speed of the winding spool is N, the slip ratio is calculated as follows. If α is defined as α = (the peripheral speed of the capstan−the linear speed of the extra fine line) / the linear speed of the extra fine line, the following expression is established.

Α = (πdn−πDN) / πDN = dn / DN−1 (1) N = 1 / (α + 1) · dn / D (2)

[0009] The slip rate is determined by the linear velocity of the ultrafine wire, the material of the lubricating oil and the ultrafine wire, the diameter of the ultrafine wire, the state of the surface of the capstan,
It is an important constant that must be determined by the tension of the ultrafine wire and the like, and the value of the slip ratio, whether too large or too small, may cause a disconnection that may hinder the drawing operation.

An example of a conventional method of controlling the slip ratio will be described with reference to FIG. The capstan driving motor 5 compares and amplifies the signal of the speed setting device 13 for setting the rotation speed of the motor by the magnitude of the voltage with the signal of the capstan tach generator 6, and amplifies the capstan driving motor controller. The control by 14 controls the rotation at a constant speed. This control system is a control for making the rotation speed of the motor 5 constant by feedback, and is not directly related to the control of the slip ratio.

In order to control the slip ratio, a slip ratio controller 15 is provided.
5, a signal indicating the rotation speed of the capstan detected by the rotary encoder 8, a signal indicating the rotation speed of the take-up spool detected by the rotary encoder 11, and a slip ratio setting for setting the slip ratio α described above. The signal from the device 16 is input. Note that the set slip ratio α is treated as a constant because the actual measurement is difficult even though the winding diameter D of the ultrafine wire gradually increases with winding.

The slip ratio controller 15 calculates the following equation (1) from each of the signals input to the slip ratio controller 15:
The calculation of the expression (2) is performed, and the result of the expression (1) is output to the slip ratio display 17 and displayed on the slip ratio display 17, and the result of the expression (2) is used for driving the take-up spool. It is output to the winding motor controller 18 as a rotation setting signal of the motor 9.

[0013]

Incidentally, recent ICs
The price of semiconductors and semiconductors has been significantly reduced due to the effect of mass production, and the demand for price reduction of bonding wires, which is one of the materials, has been increasing. For this reason, even in the drawing process, the length of a line per one drawing tends to be increased year by year in order to obtain a power saving effect. However, according to the above-described conventional technique, the winding motor control method based on the calculation of the slip ratio assuming that the winding diameter D of the ultrafine wire is constant, the difference between the initial winding diameter and the winding diameter immediately before the end of winding. The difference became too large, and as a result, the slip ratio gradually became smaller, the disconnection was more likely to occur, and this was a factor that hindered the work.

Accordingly, it is an object of the present invention to provide a method for drawing an ultra-fine wire which has solved the above-mentioned disadvantages.

[0015]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a method of drawing an ultrafine wire through a plurality of dies having a predetermined reduction rate in a lubricating oil and around a capstan. In the slip-type drawing method in which the drawing speed of the ultrafine wire and the peripheral speed of the capstan are different, a method of drawing the ultrafine wire, characterized in that the slip ratio is controlled to be constant.

[0016]

Next, a preferred embodiment of the present invention will be described with reference to the drawings.

The apparatus for carrying out the method for drawing a fine wire according to the present invention is substantially the same in mechanical structure as that shown in FIG. 1 used to describe the apparatus for carrying out the conventional method. When the method of the present invention is implemented, the only difference from the conventional method is that two rotary encoders 8 and 11 do not need to be used, and a detailed description of the apparatus will be omitted.

FIG. 2 is a schematic block diagram of a control circuit used in the method for drawing a fine wire according to the present invention. In FIG.
The capstan driving motor 5 is controlled by the controller 14 to the speed set by the speed setting device 13 in the same manner as in the prior art shown in FIG. Note that the signal representing the speed set by the speed setting device 13 is also supplied to a slip ratio controller 15 that controls the slip ratio to be constant.

The slip rate controller 15 further includes a signal from a traverse detection switch 21, a signal from a digital switch 22 for setting conditions (for selecting the diameter of an extra fine line, etc.), and a slip rate setter 16. Is input. The input signal is subjected to arithmetic processing to obtain a winding motor setting signal, and the obtained winding motor setting signal is output from the slip ratio controller 15 to the winding motor controller 18, and the winding motor controller 18 The take-up spool drive motor 9 is controlled so as to rotate accurately in accordance with the take-up motor setting signal. At this time, the slip ratio is output to and displayed on the slip ratio display 17 as in the prior art.

Next, the control method of the present invention will be described in more detail with reference to FIGS. FIG. 3 is a side view showing a state in which a very fine wire is wound, and FIG. 4 is a block diagram showing details of the slip ratio controller 15 shown in FIG. FIG.
In, D _iA represents the outside diameter of the spool, D _iB represents wound up diameter. The number of traverses at this time is M, and the coefficient β (the height of the diameter that increases for each traverse) is β _i =
( _{DiB- DiA} ) / M.

Next, in FIG. 4, considering that there are various types of the diameter of the ultrafine wire used in the method of drawing the ultrafine wire and the outer diameter of the take-up spool, there are various types of the ultrafine wire. Are actually wound in advance on winding spools having various outer diameters, and the coefficient β is actually measured. Various values of β according to the combination of the wire diameter of the ultrafine wire and the outer diameter of the winding spool are stored in a memory 30. The outer diameter of the take-up spool to be used is also stored in the memory 32 in advance. The stored data is selected by a type selection digital switch 22 that can select a type code determined by the ultrafine wire to be used and the take-up spool.

If i is selected by the type selection digital switch 22, β _i of the i-th table and the outer diameter _{DiA of the} take-up spool are input to the arithmetic circuit 34. In addition, a signal m indicating the number of traverses from the traverse detection switch 21 is input to the arithmetic circuit 34. Therefore, in this state, when the operation of the drawing apparatus is started, a signal from the traverse detection switch 21 is inputted every time the traverse mechanism is inverted, that is, every time the winding layers of extra fine wires are stacked, and the arithmetic circuit 3
In 4, the winding diameter D _im of fine wire is D _im = β _i m + D
Calculated as _iA .

The calculated winding diameter is input to another arithmetic circuit 36, which stores a signal α from the slip ratio setting device 16 and a signal n from the capstan motor setting device 13 in advance. A signal representing the diameter d of the capstan is input from the memory 38, and a setting signal N of the take-up spool driving motor is calculated from these signals. This setting signal N (N = 1 / (1 + α) · dn /
D _im ) is input to the take-up motor controller 18 as described above, and the take-up spool drive motor 9 is accurately controlled in accordance with this signal so as to keep the slip ratio constant.

[0024]

As described above in detail, according to the present invention, when winding a very fine wire, the winding diameter of the very fine wire is accurately calculated by calculation, so that the slip ratio is controlled to be constant. Therefore, a problem such as disconnection does not occur.

[Brief description of the drawings]

FIG. 1 is a perspective view of a drawing apparatus used in the method of the present invention and the prior art method.

FIG. 2 is a schematic block diagram of a control circuit used in the method for drawing an ultrafine wire according to the present invention.

FIG. 3 is a side view showing a state in which a very fine wire is wound.

FIG. 4 is a block diagram showing details of a slip ratio controller 15 shown in FIG. 2;

FIG. 5 is a schematic block diagram of a control circuit used in a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultrafine wire 2 Dice 4, 4 'Capstan 5 Capstan drive motor 6, Tach generator 9 Winding spool drive motor 10 Tach generator 13 Speed setting device 14 Capstan drive motor controller 15 Slip rate controller 16 Slip rate Setting device 18 Take-up spool motor controller 21 Traverse detection switch 22 Digital switch

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-10020 (JP, A) JP-A-63-157411 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21C 1/00 B21C 1/06 B21C 1/12 B21C 9/00

Claims (3)

(57) [Claims] 1. A method of drawing an ultrafine wire through a plurality of dies having a predetermined diameter reduction rate and around a capstan in a lubricating oil, comprising: a linear speed of the ultrafine wire and a peripheral speed of the capstan. Is different from the slip type drawing method,
A method of drawing an ultrafine wire, wherein the drawn ultrafine wire is wound by a traversing take-up spool, and the slip rate is kept constant by changing the rotation speed of the take-up spool each time the traverse is performed. 2. The method according to claim 1, wherein the slip ratio α is represented by the following equation: α = (dn / D
N-1), where d is the diameter of the captan, n is the rotation speed of the captan, D is the winding diameter of the ultrafine wire wound on the winding spool, N is the rotation speed of the winding spool, and the change in D Characterized in that α is kept constant by changing N according to the following. 3. The method for drawing an ultrafine wire according to claim 2, wherein various coefficients representing the height of the diameter that increases for each traverse are determined by a combination of the diameter of the ultrafine wire and the outer diameter of the take-up spool. The various outside diameters of the take-up spool are stored in advance, and when executing the drawing method, a signal representing the coefficient selected from the stored ones, a signal representing the outside diameter of the selected take-up spool, and a traverse are stored. Calculating the winding diameter of the extra fine wire from a signal representing the rotation of the traverse from the switch to be detected, and calculating the rotation speed of the winding spool from the value of the calculated winding diameter. Method.